A massive Microsoft outage is causing disruption across the world for airlines, banks, and retailers

• A mass IT outage is affecting flights, banks, and other organizations around the world.
• A "defect" in an update for Windows caused the issue, the cybersecurity firm CrowdStrike said.

Major airlines, banks, and supermarkets are experiencing widespread disruptions connected to a defective update issued by the cybersecurity firm CrowdStrike.

American Airlines and United Airlines issued advisories to airborne flights early Friday morning. The carriers said communication was intermittent because of issues with systems that send messages to planes, often from air-traffic control or airline operations.

Some passengers were being issued handwritten boarding passes at airports because of the disruption. At London's Heathrow Airport, travelers were advised to check their gate numbers on Google as information screens were not working.

Broadcasters and 911 lines are affected, as are grocery stores, retailers, and fast-food giants whose in-store cash registers malfunctioned.

As commuters woke up in New York City, they were told train-arrival information for the subway would not be available, though service was unaffected.

"The world grinding to a halt because of a global IT meltdown shows the dark side to technology and that relying on computers doesn't always make life easier," Dan Coatsworth, an investment analyst at AJ Bell, said.

CrowdStrike CEO George Kurtz said on X the company was "actively working with customers impacted by a defect found in a single content update for Windows hosts," adding: "The issue has been identified, isolated and a fix has been deployed."

In an interview with NBC's "Today," Kurtz apologized for the outage: "We're deeply sorry for the impact that we've caused to customers, to travelers, to anyone affected by this." He added that it "could be some time" for systems to recover.

Microsoft acknowledged the issue in an X update: "Our services are still seeing continuous improvements while we continue to take mitigation actions."

One cybersecurity expert told Business Insider there was no automatic or remote solution to the problem, meaning "every computer affected has to have some manual interaction."

The UK government was due to hold an emergency meeting to discuss the outage later on Friday.

Disruption and delays

Singapore's Changi Airport said it was manually checking in some passengers, and local media reports showed long lines at check-in counters.

A spokesperson told BI: "Due to a global outage affecting IT systems of many organizations, the check-in process for some airlines at Changi Airport is being managed manually."

At London's Luton Airport, Nick Xydias said he was stuck waiting for a Wizz Air flight to Larnaca, Cyprus.

"It's my birthday, and we'd booked a romantic trip with my wife. She'd got a new dress and everything," he told BI from a long line of frustrated passengers. "All the flights are grounded."

His flight was later canceled.

He also shared these photos:

In Australia, Melbourne Airport said it was experiencing a "global technology" issue affecting check-in procedures for some airlines. Sydney Airport also reported a global outage for airline operations and terminal services, though flights were still operating.

Delhi Airport in India also said it was affected. A passenger at Rajiv Gandhi International Airport wrote on X that he had been issued a handwritten boarding pass.

Edinburgh Airport in the UK and Berlin Airport in Germany also warned of delays.

Ryanair, Europe's largest airline, said there was "disruption across the network due to a Global 3rd party IT outage which is out of our control" and advised passengers to head to airports early.

CrowdStrike issues

Many of the affected Windows devices displayed an error message — colloquially called the "blue screen of death" — that locked users out of their computers.

CrowdStrike said a defective update caused the issue.

The outage is "one of the most significant of cyber issues of 2024," Omer Grossman of the cybersecurity company CyberArk said in a statement to BI. "The damage to business processes at the global level is dramatic."

Correction: July 19, 2024 — An earlier version of this story gave the wrong destination airport for a passenger. Nick Xydias was trying to reach Larnaca, Cyprus, not Monaco.